Table Of ContentAD-A259 560
Clinical and laboratory observations. -
following oral or intramuscular
administration of a live attenuated
hepatitis A vaccine candidate
Maria H. Sjogren*t, Robert H. Purcell*, Kelly McKee, Leonard Binn§, Philip '0
Macarthyt, John Ticehurst, Steven Feinstone", Jeffrey Caudill, Anthony See,
Charles Hoke§, William Bancroft§ and Erik D'Hondt" CA)
Clinical observations made after immunising volunteers with a live attenuatedh epatitis A A
vaccine are described. The candidate vaccine was prepared with the HMI75 strain of U
hepatitis A virus and shown to be safe, immunogenic and efficacious in experimental
animals. When the candidate vaccine was tested by oral administration in humans at
increasingd oses - 104, 10-, 106 and 107 median tissue culture infective doses (TCIDso)) - an (cid:127) S
antibody response was not observed at any, dose. Volunteers who received similar doses by "I
the intramuscularr oute developed antibody to hepatitis A three weeks after immunization
with 106 or 107 TCID-,(. The antibody response .was sustained for the 12 weeks of the
observation period. All volunteers remained healthy' with normal results from liver tests
throughout the monitoring period. Further clinical observations of this product are in
progress.
Keywords: Hepatitis A. Ora) hepatitis, liver
INTRODUCTION obtained from each volunteer.
Although inactivated hepatitis A vaccines are in the pro- In this clinical trial, volunteers received increasing
cess of preparation, logistical problems such as multiple titres of a live, attenuated hepatitis A vaccine by the oral
injection and cost of the product could be significant route. Later, a second group of volunteers received simi-
impediments to implementing a worldwide immuniza- lar doses by the intramuscular route. Eight volunteers
tion programme. A live, attenuated hepatitis A vaccine, received the live attenuated hepatitis A vaccine by the
if safe and immunogenic, would be a candidate to use in oral route in the following manner: two received a 104
massive eradication programmes. Investigators at the median tissue culture infective dose (TCID%), two
National Institutes of Health in Maryland and investi- received 101 TCID50, two received 106 TCID,0 and two
gators at SmithKline Beecham Biologicals, Belgium received 107 TCID5,. Six volunteers received the vaccine
prepared the present candidate vaccine. Investigators by the intramuscular route in the following manner: two
from the US Army performed the first human trial of this received 101 TCID_, two received 106 TC1D5, and two
preparation. Details of this trial are described, received 101 TCID50
MATERIAL AND METHODS Candidate vaccine
Study group The vaccine was prepared with the HM1 75 strain of
The study was approved by Institutional Review Coin- hepatitis A virus (HAV). HAV was first propagated in
mittees. Before enrollment, informed consent was African green monkey kidney cells (AGMKC) and then
adapted to human MRC-5 fibroblast cells. Attenuation
was attained by serial blind passages. An earlier publica-
The work was performed at the following institutions: tDiv- tion described the vaccine preparation in AGMKC and
ision of Medicine, United States Army Medical Research pre-clinical studies in chimpanzees and marmosets'. The
Institute of Infectious Diseases, Fort Detrick, Frederick, MD M RC-5 adapted vaccine candidate used in this study was
21702, USA. :National Institutes of Health, Bethesda, MD,
USA. 'Walter Reed Army Institute of Research, Washington, also tested in chimpanzees and marmosets. These pre-
DC. USA. 'Food and Drug Administration, Rockville, MD, clinical studies demonstrated that the vaccine was safe,
USA. 'SmithKline Beecham Biologicals, Rixensart, Belgium. immunogenic and efficacious in experimental animal
*To whom correspondence should be addressed models.
0264-410X./g2J100S13&--3 92 12 30 058
1992 Butterwor9h-HeinemannLtd Vaccine, Vol. 10, Suppl. 1, 1992 S135
Live hepatitisA vaccine: M.H. Sjogren et al.
Clinical monitoring 100
Volunteers were admitted to a closed clinical ward at
the US Army Medical Research Institute of Infectious >
Diseases, Fort Detrick. M:'ryland. Each volunteer 80
remained on the ward for three days after immunization. .o
Local or systemic side effects were monitored during the *
admission period and for 12 weeks following the immu- (cid:127) 60
nization. Volunteers were asked to return at 8 and 12
months for serological follow-up. Vaccine was adminis- 2f
tered as a single dose of 1.0 ml orally or intramuscularly .- 0
in the deltoid area.
r-
Collection and testing of clinical samples > 20
<
Sera were obtained prior to immunization and once a T
week for the next 12 weeks. In volunteers who completed C
the appropriate follow-up time, sera were also obtained <
at 6 and 12 months after initial administration of vac-
cine. Serum specimens were tested for alanine amino- Time (weeks)
transferase (ALT) and antibody to hepatitis A. ALT was Figure I Antibody to hepatitis A following immunization with live, atte-
tested with a Kodak EKTA Chem 700XR analyser nuated vaccine. Antibody to hepatitis A was tested by standard HAVAB
(Rochester, NY. USA): normal values were 0-50 lU/ml. (. l) and neutralizing antibody (*).V accine was administered at time
zero. _, 106 TCIDO; 0. 10, TCOD,. Neutralizing antibody was present at
Antibody to hepatitis A was tested by four different various titres (see text)
methods, including a commercial radioimmunoassay
(HAVAB. Abbott Laboratories. North Chicago. IL, dose. 1gM anti-HAV was not detected in any of the
USA) and an enzyme-linked immunoassay developed by volunteers who received the vaccine orally. Sera from
SmithKline Beecham Biologicals (SKB-ELISA). which volunteers who received 107 TCID, i.m. had detectable
was more sensitive than the standard HAVAB. in which 1gM anti-HAV.
a level of > 20 mlU ml was considered positive. Selected Stools from all volunteers who received the oral vac-
sera were tested by the radioimmunofocus inhibition test cine were negative for hepatitis A virus, while those from
(RIFIT) for neutralizing antibody to hepatitis A. With volunteers who have received the vaccine by the intra-
this test, a serum titre of > 1: 10 was considered positive2, muscular route are in the process of being tested.
In the fourth method, sera were tested for immunoglobu-
lin M (IgM) anti-HAV by commercial radioimmunoas-
say (HAVAB-M. Abbott Laboratories). DISCUSSION
Stools were collected from the volunteers two to three Although only a small number of volunteers received the
times per week for the first 12 weeks and were tested for vaccine orally, the vaccine was not immunogenic in
the presence of hepatitis A virus by radioimmunoassay3 them. This is probably due to overattenuation of the
and molecular biology techniques4. virus, although other causes, such as inactivation in the
gastrointestinal tract or too small an inoculum, should
RESULTS be considered. The vaccine was safe and immunogenic bN
the intramuscular route at doses of 106 and 10- TCID(cid:127),.
All volunteers remained healthy during the follow-up The antibody response was prompt: anti-HAV was
period (12 weeks to one year). No systemic complaints observed within 3 weeks of immunization, persisted
were present immediately after immunization or during during the period of observation and did not diminish in
long-term follow-up. Serum ALT levels remained titre. Such a response to a single inoculation of a prep-
normal in all 14 individuals during the period of obser- aration which lacked an adjuvant is remarkable. The
vation. presence of IgM anti-HAV in volunteers who received
Antibody to hepatitis A was not observed in any of the 10' TCID, without evidence of hepatitis is suggestive of
eight volunteers who received the vaccine by the oral asymptomatic replication of the virus. Final evaluation
route or in the two volunteers who received l05 TCIDS must await the results of attempts to detect HAV in
by the intramuscular (i.m.) route. The four volunteers stools of the volunteers.
who received higher doses of vaccine i.m. (106 TCID , or Two other groups of investigators have reported clini-
5
10' TCIDO) all had detectable antibody by ELISA as cal observations after immunizing volunteers with live
early as 3 weeks after immunization. Detectable levels attenuated hepatitis A vaccines. Provost et al.5 described
persisted for the 12 weeks of observation. Figure I shows the F and F' variants of the CR326 hepatitis A virus
the immune response of one of the volunteers who strain. While the F variant was highly immunogenic, it
received l06 TCID,, and another who received 107 also caused abnormal serum ALT levels in a substantial
TCIDq, vaccine. Selected sera tested for neutralizing proportion of individuals. The F' variant was more atte-
antibody had titres ranging from 1:10 to 1:40 in the nuated: 10 of I 1 volunteers had demonstrable anti-HAV
volunteer who received a 106 dose and 1:40 to 1:2560 in by modified HAVAB without abnormal ALT levels
the volunteer who received a 101 dose. The time of when the vaccine candidate was administered by the
appearance of neutralizing antibody is also depicted in subcuianeous route.
Figure L. The commercial HAVAB assay detected anti- Another recent publication from this group of investi-
HAV in only one of the volunteers, who received the 10' gators has described further work with the F' variant".
S136 Vaccine, Vol. 10, Suppl. 1, 1992
Live hepatitis A vaccine: M.H. Sjogren et al.
They observed that the immunogenicity of the product is as official or as reflecting the views of the Department of
dose-dependent. 10" TCI,, evoked an antibody res- the Army or the Department of Defense.
ponse in 100% of the volunteers within 9 weeks after The authors are grateful to the outstanding assistance
immunization. Lower doses were immunogenic in a of the nursing and laboratory staff at the US Army
smaller percentage of volunteers and anti-HAV was Medical Research Institute of Infectious Diseases at Fort
observed 4 to 6 months after immunization. Detrick. We thank Ms Judy Reichard for secretarial
Chinese investigators have recently described studies assistance. We acknowledge the staff at the US Army
of a live attenuated hepatitis A vaccine prepared from Medical Material Development Activity at Fort Detrick
the H2 strain of HAV'. Twelve volunteers received the for financial support and scientific encouragement.
vaccine by the subcutaneous route. All volunteers {C US Government.
remained healthy and had detectable anti-HAV by week
3 after inoculation. Follow-up of these individuals REFERENCES
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